In language comprehension, it is of central importance to be able to rapidly acces lexical information stored in the mental lexicon and to be able to maintain that information in working memory for integration with other information. Recently, reading reseachers have suggested a number of code-related processing deficits which serve to distinguish these poor readers from good readers. These include a general deficit in using any sensory codes to access the lexicon, a general deficit in accessing phonological codes alone or in maintaining these codes in working memory as well as a specific deficit in accessing lexical information from printed words themselves. The research outlined in this proposal investigates those word-recognition processes which are crucial to the reading process, focusing on the ability of children at different stages of reading development to make use of phonological, orthographic, and semantic information in processing both spoken and written language. A series of experiments is proposed in which subjects are asked to monitor word lists in order to detect a word that rhymes with, or else one that is a category exemplar of, a given cue word. The experiments are devised to evaluate the course of development of the ability of the child to access lexical information, and the ability of the child to maintain lexical codes in working memory. These abilities are further differentiated by: the modality (i.e. visual or auditory) of presentation, and the code (phonological or orthographic) which is used. This research will then provide a rich data base bearing on a number of central questions about the relationship of code use and reading including: (1) Do good and poor readers differ in their abilities to access lexical codes generally, regardless of specific code or modality of presentation? (2) Do good and poor readers differ in their abilities to maintain codes in working memory? And (3) are there identifiable patterns or strategies of lexical access and code maintenance which differentiate subgroups of good and poor readers?